Pulverizer.



.No. 895,917; "-PATENTED AUG. 11, 1908.

J. VANDEGRIFT.

PULVHRIZER. Arrmouron 11.21) no. 6, 1907.

' tame/Mod UNITED STATES PATENT OFFICE.

JACOB VANDEGRIFT, OF NORTH CATASAUQUA, PENNSYLVANIA, ASSIGNOR OF TWO-THIRDS TO JOHN HUNTER, OF NORTH OATASAUQUA, PENNSYLVANIA.

PULVERIZER. i

Patented Aug. 1 1, 1908.

Application filed December 6, 1907. Serial No. 405,451.

To all whom it may concern:

a citizen of the United States, residing at North Oatasauqua, in the county of Northampton and State of Pennsylvania, have invented certain new and useful Improvements in Pulverizers, of which the following is a specification.

My invention relates to that class of grinding mills in which cylindrical rollscapable of rotating about their axes are revolved within an outer grinding ring, and my invention consists in providing a supplemental grinding ring inside the rolls and concentric with,

the outer ring, and in providing a central discharge opening together with certain details of construction, as fully set forth hereinafter, and as illustrated in the accompanying drawing, in which Figure 1 is an elevation of sufficient of a pulverizer to illustrate my invention; Fig. 2 is a sectional plan on the line 22, Fig. 1.

The mill is provided with the usual grinding rolls A, A, which are rotatable with or on the shafts'l, the latter being carried by a rotating cross head B and supported so as to swing outward under centrifugal action, all as in any of the Well known grinding or pulverizing mills, so that the grinding or pulverizing rolls are both rotatable upon their axes, and revolve around the axis of the cross head B; a

The base O is suitably constructed to support the usual grinding ring D which may be connected detachably to or form a part of the base so as to present an outer grinding face :20, between which and the rolls, as the cross head B revolves, the material may be pulverized as usual.

In addition to the grinding face 00 however I provide a supplemental parallel or concentric grinding face y which is preferably the inner face of a detachable grinding ring E se-' cured to a hub 8 of the base, and the parts are so proportioned that the circular channel in which the rolls A are revolved is only so much wider than said rolls, that when the latter are in operation the material being pulverized will be carried by the rotation of the rolls between the latter and inner ring with suflicient friction to very materially aid in reducing or grinding the same. Thus, assuming the cross head to rotate in the direction of the arrow 8, Fig. 2, the grinding rolls will be rotated in the direction of the arrow 25,

and the material will not only be crushed by the pressure of the grinding rolls against the face a, of the outer ring, but will be carried by the rotation of the rolls into the space between the latter and the face 'y of the inner ring, and in practice the grinding effect upon the inner ring will equal or nearly equal that secured by the action of the rolls upon the outer ring. A i

The finely pulverized ma. erial may be car ried outward and downward through peripheral openings as usual in these mills, such for instance as shown in E. G. Griffins patent No. 520,958, and others, but it has been found that these openings which. are necessarily narrow are apt to become clogged, and I therefore provide a central discharge opening w, which in the const ruction shown may be secured by using a hollow hub 3, and with this. discharge opening may communicate t he usual draft fan, t he opening being of such size that no possible clogging can result, and to re Ii ain the coarser parf icles within the mill I arrange above the said central opening a screen J which may be support ed by a skeleton frame K, or otherwise. By this means I secure a discharge opening of such large area that no possible clogging can result. t will I be evident that t his arrangement of the discharge opening or discharge opening and screen may be used in connection with those of the ordinary Griffin mills even if the inner grinding face or ring is not employed.

WVithout limiting myself to the cons'ruction and arrangement of par 'IS shown, I claim as my invenion:

1. In a pulverizer the combination of cylindrical rolatable grinding rolls, means for sustaining the said rolls and for rev'olvin the same, a base, and concentric grinding rings support ed thereby equidistant from the rolls when the latter are at rest.

2 In a pulverizer, a base provided wi'h a central hollow hub 3 combined with concen trio grinding rings E, D, the inner ring fitted to said hub, and rotatable grinding rolls, and means for sustaining the said rolls normally in a position to play beiw'ecn said rings and equidistant from both as set forth.

In testimony whereof I affix my signature in presence of two witnesses.

JACOB VANDEGRIFT.

\Vitnesses:

JOHN HUNTER, AUSTIN A. GLIOK. 

